Me, in a nutshell

I'm frustrated because I lack motivation and concentration due to what feels like physical fatigue but has no discernable mental basis. This makes graduate school a daunting chore, when at my full capability it would be a cakewalk. These problems have persisted for years and the stress it puts on people around me tends to drive people away (i.e. my ex-fiancé, which I'm also still not properly over 6-7 months later) so I feel lonely, and anxious about the people I do talk to because it seems like if I say the wrong thing they might abandon me.